What is dental plaque?

dental procedure
Without proper oral hygiene, plaque forms on our teeth, hardens and turns to tartar, which can only be removed with ultrasonic tools and fine dental picks.
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Plaque likes to make itself at home in our mouths. It comes on strong after we eat food and is a soft, miniscule mix of bacteria and acid that grows into a filmy yellow coating on teeth. Just like a messy houseguest, if the plaque is left alone to hang out and have friends over -- more and more bacteria -- eventually every surface and crack and crevice needs a thorough cleaning. And just as a layer of moisture and gunk leaves rings on coffee tables and dingy stains and crust on upholstery, plaque settles in, and spreads out, and over time hardens to the point that you can feel it on your teeth. By then, it has worn out its welcome and needs to be forcibly evicted for the greater good of the teeth.

Routine oral hygiene goes a long way toward keeping plaque at bay, but it is the nature of plaque bacteria to stick to other bacteria in the mouth, so even the most valiant efforts in the fight require the right tools and trained allies: dentists and hygienists [source: McDonald]. Just 20 minutes after we eat, food particles, bacteria, sugars, acids and saliva combine, and become plaque. This short window of time is when bacteria are most active [source: NIH]. Starchy, sugary and sticky foods are especially effective for plaque growth because of their acid content and ability to cling to teeth.


As early as 5000 B.C. people were looking for the source of tooth decay, arriving at the conclusion that the cause was "tooth worms." And until the invention of a boar-bristled toothbrush in 1498 and a nylon toothbrush in 1938, cultures worldwide have used tree bark and twigs, called chew sticks, to clean their teeth -- still a common practice in parts of Asia and Africa. Dental floss was invented in about 1815, though evidence of toothpicks and between-teeth cleaning goes back thousands of years [sources: JADA; LOC; Oral-B].

While the cause of plaque formation and tooth decay isn't actual worms, in 1674 Antonie van Leeuwenhoek, a Dutch microscope hobbyist who wasn't a trained scientist, found worm-like, moving bacteria while studying samples from inside his own mouth. His informal studies led to more scientific research into bacteria and its residue, or biofilm [source: Encyclopaedia Britannica]. Ancestors of those same bacterial worms are alive and well and thriving in evolved forms in the 21st century, and people worldwide still strive to get rid of them.

Can we get the upper hand in this bacteria battle? We'll get up close and personal with plaque before showing it the door, next.


Finding Plaque

Plaque is very personal. It forms from countless combinations of foods, individual acid and moisture levels in a person's mouth, and internal and exterior bacteria from any number of sources. Back molars, the ridges along dental work, and the lower faces of teeth near the gum line are places where plaque accumulates the most, and these areas often are harder to get to with a quick brushing. Tooth decay and bad breath are some obvious signs that plaque bacteria is thriving in a mouth, but these problems develop long after plaque has started to form.

You can't see plaque with the naked eye until decay from plaque forms, but you can feel the sticky film, note some dull sliminess and just know it's there if you've missed some appointments with the toothbrush. You can use disclosing tablets, which typically look like little red pills, if you want to see where plaque is forming. Chewing a disclosing tablet releases a safe dye that mixes with saliva and attaches itself to areas covered with plaque bacteria. Some dental professionals use the tablets to teach young children where they need to steer their toothbrushes, and adults can use the dye after brushing to see what areas they may be missing.


Removing plaque is important for oral health. Bacteria and acids wear down tooth enamel, the protective covering of teeth, and over time, cavities, also called dental caries, form. In addition to causing cavities, plaque can lead to gum problems. As it's forming, plaque is soft, but if not removed after eating it can harden around the base of and in between teeth, making it harder to clean thoroughly at the gum line.

Hardened plaque is called tartar or calculus, and it can irritate gums and cause bleeding and swollen gum tissue, both signs of gingivitis. Gums can recede, pulling away from the surface of teeth and creating pockets for further plaque debris as well. More than half of all people in the United States have gingivitis, which can lead to gum, or periodontal, disease, but gingivitis is very treatable in its early stages. Gum disease is preventable once gingivitis is found, but it is not reversible -- only treatable.

Poor gum health from plaque build-up also is linked with physical conditions outside of the mouth, including heart disease, low infant birth weights and blood sugar issues, for example. Although gum disease hasn't been definitively identified as a cause of such health problems, it is commonly found in connection with these conditions [source: NIH]. In the case of heart disease, the plaque that causes hardened arteries and blocks blood flow is not the same plaque film found on the teeth, but some strands of bacteria that lead to gum disease and cavities also have been shown to get into the bloodstream, leading to clogged arteries. A direct link, however, hasn't been identified [sources: Harvard University; Ray].

Getting at the plaque while it's still soft rather than being soft on plaque can prevent many of these issues. We'll brush up on how, next.


Fighting Plaque

After thousands of years of study, innovation and treatment, some of the best advice for fighting plaque remains the same: brush after meals and floss daily. Cleaning teeth after eating reduces the build-up of bacteria that's inevitable if it isn't sloughed off teeth and spit out. Interdental cleaning, which includes flossing and using picks or gum stimulators to dislodge food particles, is one of the best ways to keep plaque from forming and spreading between teeth and into the gum line. Rinses are a third component for many, and alcohol-free, fluoride and anti-bacterial options can help remove particles and plaque film, as well as freshen breath. Mouth rinses should not be a replacement for brushing or flossing, though, but as an added hygiene tool or a specific recommendation by a dental professional [source: ADA].

Products help us purge plaque by repelling bacteria, and specialized professional products such as sealants can be applied to teeth in a dentist's office. Sealants are made from a plastic material, and when painted on teeth, especially the plaque-attracting back molars, sealants fill in crevices and dry to form a shield that protects tooth enamel from decay. Both children and adults can benefit from sealants, but they don't replace daily cleanings and aren't for everyone. A dentist can advise whether they will be effective [source: ADA].


Even with our very best efforts -- brushing at least twice a day, flossing, rinsing and more -- plaque can't be completely prevented and eliminated. Regular dental office cleanings and checkups are important for keeping teeth and gums healthy. Once plaque hardens, no toothpaste, brush, rinse or floss can tear it down: It needs to be removed with ultrasonic tools to vibrate away large stuck-on pieces and finer scaling tools to pick off smaller tartar growths. Cleaning and removing plaque is also called prophylaxis, which is a term for a treatment that aims at preventing disease, and in the case of dental cleaning, it prevents tooth decay and gum disease and removes stains. Polishing comes after a thorough cleaning, and it provides a smooth finish to tooth surfaces, but it has little hygienic benefit and is instead mainly cosmetic [source: ADHA].

All of this dental maintenance works best in combination with a healthy diet and post-meal plan. Foods high in carbohydrates and those with a lot of acid stick to and eat away at tooth enamel, and many foods aside from sweets break down into sugars. Brushing soon after eating and cleaning all-around the inside of the whole mouth will inhibit plaque growth. Sugary sweets are loaded with glue-like carbs for icing your teeth with bacteria and acids, so planning a toothbrush attack after a sweet-tooth attack is a good battle plan. Plaque is a friendly and fast-growing "party in your mouth" if it isn't given its walking papers soon after settling in. Brushing well, flossing often and never going to bed without gently evicting the bacteria first can help keep your mouth clean and healthy.

Links to more tips for removing slime from your smile follow.


Lots More Information

Related Articles

More Great Links

  • American Dental Association (ADA). "Cleaning Your Teeth and Gums." ADA.org. 2011. (Aug. 29, 2011) http://www.ada.org/2624.aspx
  • American Dental Association (ADA). "Dental Sealants." ADA.org. 2011. (Sept. 4, 2011) http://www.ada.org/3026.aspx
  • American Dental Association (ADA). "Mouthrinses." ADA.org. 2011. (Aug. 29, 2011) http://www.ada.org/1319.aspx
  • American Dental Association (ADA). "Plaque." ADA.org. 2011. (Sept. 1, 2011) http://www.ada.org/3101.aspx
  • American Dental Hygienist's Association (ADHA). "American Dental Hygienist's Association Position on Polishing Procedures." 2011. (Sept. 1, 2011) http://www.adha.org/profissues/polishingpaper.htm
  • American Dental Hygienist's Association (ADHA). "Frequently Asked Questions." 2011. (Sept. 1, 2011) http://www.adha.org/faqs/index.html
  • Encyclopaedia Britannica. "Tooth." Britannica.com. 2011. (Sept. 1, 2011) http://www.britannica.com/EBchecked/topic/599469/tooth/7342/Diseases-of-teeth-and-gums?anchor=ref225480
  • Harvard University Medical School. "Heart Disease and Oral Health: Role of Oral Bacteria in Heart Plaque." Harvard.edu. February 2007. (Sept. 2, 2011) http://www.health.harvard.edu/press_releases/heart-disease-oral-health
  • Journal of the American Dental Association (JADA). ADA.org. "Exploring the History of Dentistry." 2011. (Sept. 1, 2011) http://jada.ada.org/content/135/11/1643.full
  • Library of Congress (LOC). "Who Invented the Toothbrush and When Was It Invented?" LOC.gov. Aug. 23, 2010. (Sept. 2, 2011) http://www.loc.gov/rr/scitech/mysteries/tooth.html
  • McDonald, Kim "Chemists Discover Most Naturally Variable Protein in Dental Plaque Bacterium." ScienceDaily.com. Aug. 23, 2011. (Sept. 2, 2011) http://www.sciencedaily.com/releases/2011/08/110822154745.htm
  • National Institutes of Health (NIH). "Dental Cavities." NIH.gov. 2011. (Sept. 2, 2011) http://www.nlm.nih.gov/medlineplus/ency/article/001055.htm
  • National Institutes of Health (NIH). "Periodontal (Gum) Disease; Causes, Symptoms, and Treatments." NIH.gov. April 2010. (Sept. 2, 2011) http://www.nidcr.nih.gov/nidcr2.nih.gov/Templates/CommonPage.aspx?NRMODE=Published&NRNODEGUID={CE246689-D899-4CC7-B68A-805AD910F4E7}&NRORIGINALURL=%2fOralHealth%2fTopics%2fGumDiseases%2fPeriodontalGumDisease.htm&NRCACHEHINT=Guest#canPeriodontal
  • National Institutes of Health (NIH). "The Story of Fluoridation." NIH.org. 2011. (Sept. 5, 2011) http://www.nidcr.nih.gov/oralhealth/topics/fluoride/thestoryoffluoridation.htm
  • Oral-B. "The History of Dental Floss." Oral-B.com. 2011. (Sept. 4, 2011) http://www.oralb.com/topics/history-of-dental-floss.aspx
  • Ray, C. Claiborne. "Q & A: Perils of Plaque." Aug. 22, 2006. (Sept. 1, 2011) http://query.nytimes.com/gst/fullpage.html?res=9E0DE0DA123EF931A1575BC0A9609C8B63
  • Science Daily. "Cavity Fighting Candy." Science.Daily.com. Nov. 1, 2008. (Sept. 2, 2011) http://www.sciencedaily.com/videos/2008/1109-cavity_fighting_candy.htm